1 files changed, 39 insertions, 2 deletions

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index c286e75ec087..bfcde949c7f8 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -255,7 +255,6 @@ static void bpf_map_free_deferred(struct work_struct *work)
 
         bpf_map_uncharge_memlock(map);
         security_bpf_map_free(map);
-        btf_put(map->btf);
         /* implementation dependent freeing */
         map->ops->map_free(map);
 }
@@ -276,6 +275,7 @@ static void __bpf_map_put(struct bpf_map *map, bool do_idr_lock)
         if (atomic_dec_and_test(&map->refcnt)) {
                 /* bpf_map_free_id() must be called first */
                 bpf_map_free_id(map, do_idr_lock);
+                btf_put(map->btf);
                 INIT_WORK(&map->work, bpf_map_free_deferred);
                 schedule_work(&map->work);
         }
@@ -2011,6 +2011,12 @@ static int bpf_map_get_info_by_fd(struct bpf_map *map,
         info.map_flags = map->map_flags;
         memcpy(info.name, map->name, sizeof(map->name));
 
+        if (map->btf) {
+                info.btf_id = btf_id(map->btf);
+                info.btf_key_id = map->btf_key_id;
+                info.btf_value_id = map->btf_value_id;
+        }
+
         if (bpf_map_is_dev_bound(map)) {
                 err = bpf_map_offload_info_fill(&info, map);
                 if (err)
@@ -2024,6 +2030,21 @@ static int bpf_map_get_info_by_fd(struct bpf_map *map,
         return 0;
 }
 
+static int bpf_btf_get_info_by_fd(struct btf *btf,
+                                  const union bpf_attr *attr,
+                                  union bpf_attr __user *uattr)
+{
+        struct bpf_btf_info __user *uinfo = u64_to_user_ptr(attr->info.info);
+        u32 info_len = attr->info.info_len;
+        int err;
+
+        err = check_uarg_tail_zero(uinfo, sizeof(*uinfo), info_len);
+        if (err)
+                return err;
+
+        return btf_get_info_by_fd(btf, attr, uattr);
+}
+
 #define BPF_OBJ_GET_INFO_BY_FD_LAST_FIELD info.info
 
 static int bpf_obj_get_info_by_fd(const union bpf_attr *attr,
@@ -2047,7 +2068,7 @@ static int bpf_obj_get_info_by_fd(const union bpf_attr *attr,
                 err = bpf_map_get_info_by_fd(f.file->private_data, attr,
                                              uattr);
         else if (f.file->f_op == &btf_fops)
-                err = btf_get_info_by_fd(f.file->private_data, attr, uattr);
+                err = bpf_btf_get_info_by_fd(f.file->private_data, attr, uattr);
         else
                 err = -EINVAL;
 
@@ -2068,6 +2089,19 @@ static int bpf_btf_load(const union bpf_attr *attr)
         return btf_new_fd(attr);
 }
 
+#define BPF_BTF_GET_FD_BY_ID_LAST_FIELD btf_id
+
+static int bpf_btf_get_fd_by_id(const union bpf_attr *attr)
+{
+        if (CHECK_ATTR(BPF_BTF_GET_FD_BY_ID))
+                return -EINVAL;
+
+        if (!capable(CAP_SYS_ADMIN))
+                return -EPERM;
+
+        return btf_get_fd_by_id(attr->btf_id);
+}
+
 SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, size)
 {
         union bpf_attr attr = {};
@@ -2151,6 +2185,9 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz
         case BPF_BTF_LOAD:
                 err = bpf_btf_load(&attr);
                 break;
+        case BPF_BTF_GET_FD_BY_ID:
+                err = bpf_btf_get_fd_by_id(&attr);
+                break;
         default:
                 err = -EINVAL;
                 break;